Sintering and characterization of bismuth-oxide-containing zinc oxide varistors

Zinc oxide with different contents of Bi2O3 was prepared via a solid-state reaction to be used as varistors. Sintering was performed at 1200 and 1300 °C. Densification was achieved through liquid-phase sintering. A zincite phase, together with bismuth zinc oxide (Bi7.65Zn0.35O11.83) and zinc bismuth oxide (Bi25.33Zn0.667O40) phases, was formed at 1200 °C. A free Bi2O3 phase was still present at 1200 °C. Only the zincite phase was developed, and the other phases disappeared at 1300 °C. I–V characteristics show nonlinear behavior in all samples. The behavior was expected to be a result of the development of intergranular phases that crystallized from the Bi-rich liquid phase.